– Greenhouse gases continued to climb: Major greenhouse gas concentrations, including carbon dioxide (CO2), methane and nitrous oxide, continued to rise during 2013, once again reaching historic high values. Atmospheric CO2 concentrations increased by 2.8 ppm in 2013, reaching a global average of 395.3 ppm for the year. At the Mauna Loa Observatory in Hawaii, the daily concentration of CO2 exceeded 400 ppm on May 9 for the first time since measurements began at the site in 1958. This milestone follows observational sites in the Arctic that observed this CO2 threshold of 400 ppm in spring 2012.

– Warm temperature trends continued near the Earth’s surface: Four major independent datasets show 2013 was among the warmest years on record, ranking between second and sixth depending upon the dataset used. In the Southern Hemisphere, Australia observed its warmest year on record, while Argentina had its second warmest and New Zealand its third warmest.

– Sea surface temperatures increased: Four independent datasets indicate that the globally averaged sea surface temperature for 2013 was among the 10 warmest on record. El Niño Southern Oscillation (ENSO)-neutral conditions in the eastern central Pacific Ocean and a negative Pacific decadal oscillation pattern in the North Pacific. The North Pacific was record warm for 2013.

– Sea level continued to rise: Global mean sea level continued to rise during 2013, on pace with a trend of 3.2 ± 0.4 mm per year over the past two decades.

– The Arctic continued to warm; sea ice extent remained low: The Arctic observed its seventh warmest year since records began in the early 20th century. Record high temperatures were measured at 20-meter depth at permafrost stations in Alaska. Arctic sea ice extent was the sixth lowest since satellite observations began in 1979. All seven lowest sea ice extents on record have occurred in the past seven years.

– Antarctic sea ice extent reached record high for second year in a row; South Pole station set record high temperature: The Antarctic maximum sea ice extent reached a record high of 7.56 million square miles on October 1. This is 0.7 percent higher than the previous record high extent of 7.51 million square miles that occurred in 2012 and 8.6 percent higher than the record low maximum sea ice extent of 6.96 million square miles that occurred in 1986. Near the end of the year, the South Pole had its highest annual temperature since records began in 1957.

– Tropical cyclones near average overall / Historic Super Typhoon: The number of tropical cyclones during 2013 was slightly above average, with a total of 94 storms, in comparison to the 1981-2010 average of 89. The North Atlantic Basin had its quietest season since 1994. However, in the Western North Pacific Basin, Super Typhoon Haiyan – the deadliest cyclone of 2013 – had the highest wind speed ever assigned to a tropical cyclone, with one-minute sustained winds estimated to be 196 miles per hour.

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By 2050 or so, the human population is expected to pass nine billion. Those billions will be seeking food, water and other resources on a planet where humans are already shaping climate and the web of life. Dot Earth was created by Andrew Revkin in October 2007 -- in part with support from a John Simon Guggenheim Fellowship -- to explore ways to balance human needs and the planet's limits.